The present invention relates generally to tennis rackets--their design, construction and manufacture. More particularly, the present invention relates to an improved tennis racket having a head portion shaped for optimum performance and an improved string mounting system. The present invention also relates generally to materials and methods for making composite material tennis rackets. More particularly, the present invention relates to a tennis racket frame made from ceramic fiber composite materials which exhibit increased durability and wear resistance while still providing a racket frame which is lightweight, strong and flexible.
Tennis rackets basically include a head portion, a handle and a neck portion which connects the handle to the head. In general, one or more structural supports or yokes are provided which extend across the neck portion in order to strengthen the racket and provide a location for strings to be mounted at the bottom of the racket head. Numerous different head designs have been proposed in the past to provide a racket with optimum performance characteristics. It usually is desirable to provide a racket which has as large a "sweet spot" as possible. The "sweet spot" of a racket is that area of the racket head which when contacted by the ball during the tennis swing provides optimum reproducible and controllable hitting by the player. It would be desirable to provide a tennis racket head which increases the size of the sweet spot present in the racket head. It would also be desirable to provide a yoke structure extending across the racket neck which increases the strength and structural integrity of the racket neck.
Another important consideration in designing a tennis racket frame is the particular material utilized in fabricating the racket. Wood and metal racket frames have been in common use for many years. More recently, racket frames made from composite materials such as resin impregnated graphite, glass and boron fibers have become available. Composite material rackets made from graphite fibers have been particularly popular due to their high strength and light weight. One problem with graphite rackets is that they tend to be easily abraded when struck against the tennis court or other hard surfaces. It would be desirable to provide a composite material racket having the desirable light weight and structural strength of graphite while being more durable and resistant to abrasion. Graphite rackets also tend to be very rigid and inflexible. In general, a certain amount of racket flexing is desired during and after ball contact. It would be desirable to provide a composite material racket which is more flexible than graphite fiber rackets.
As is well known, composite material rackets are generally made by forming uncured, resin impregnated fibers into a tennis frame precursor and then curing the composite material to form the finished tennis racket frame. In the head portion of the tennis racket, string holes must be provided for mounting the tennis strings. In general, the string holes are molded as part of the frame or drilled into the tennis frame after curing. Protective grommets or a protective grommet strip is the positioned around the head portion to protect the strings as they pass through the string holes from abrasion, cutting and breakage. It would be desirable to provide a tennis racket structure in which some other means for protecting the tennis strings is provided other than the individual grommets or grommet strips presently in use.
It is an object of the present invention to disclose and provide a tennis racket which is made from a composite material which provides equal or better performance characteristics than graphite composite rackets while providing increased durability and abrasion resistance.
An additional object of the present invention is to disclose and provide a tennis racket having a head portion with an improved string mounting configuration which is easily manufactured and provides optimum protection of the tennis strings at the point of contact with the tennis frame.